Upgrading sub to get a live feel.

Hello Watcher,

     Great, just so we're on the same page you need to:
1. Complete your bass system by positioning your two SBs using the crawl system.

2. Order a pair of speaker stands for your JBL 4319s. I think the best place to search is eBay and google, just search for "speaker stands for  JBL 4319 speakers" on either.  You'll probably get even better deals on them if you'll accept used ones in good condition.  
     The exact height of the stands is very important.  You should measure A. the distance from the floor to the middle of your ears when seated at your listening seat. Then measure B. the distance from the bottom of one of your 4319s to the middle of the tweeter.  Take measurement A and subtract measurement B and you'll have the exact height required for the height of your speaker stands.  
     My assignment is writing a procedure for you on how to properly position your 4319s in relation to your listening seat and how to best adjust the volume, crossover frequency and phase controls on your subs for the seamless blending or integration of your two systems. 
     Just a heads-up, when you receive the speaker stands and it's time to follow the procedures, things will be easier if you can recruit an assistant to help you out.  Without an assistant, you'll be going back and forth way too many times between your listening seat and each sub and you'll probably wind up exhausted by the time you're done. 
     Send me a pm or post again when you order the speaker stands.

Thanks,
  Tim
    

I already have some speaker stands I can use and the current set up has the tweeter aligned to ear level.

Hello Watcher,

     Excellent, I'll try to complete the procedures today.  

Later,
Tim

I’m going to come at this issue from a different perspective. Fully agree with comments about deep bass being omnidirectional (or non-directional) in most settings. One failing of most audio bass setups (full range or subs), to me, is lack of control. It is relatively easy to get the tone of the bass notes pretty OK. But getting tight control of large woofer excursions is another. How often do people actually hear the timbre of the instruments producing the bass in their systems? One approach to sub-bass control is to throw mega-watts of power at it, probably better conceived as providing max feasible current to drive big bass flappers. Another, more elegant, approach is to employ motional-feedback in the bass amp circuitry. In this schema, the bass amp incorporates circuitry that senses the back-EMF produced by woofer coils when distortion begins to occur then, near-instantaneously, alters the output signal to correct and cancel said distortion. Audible result is to tighten up the bass output which, in turns, makes the woofer emit a sound that more faithfully replicates the original waveform captured in the recording. Loose, flabby bass is eliminated. Some self-powered subs employ this method. The old (1970’s) Phillips motional feedback speakers (full range self-powered bookshelf speakers) also did this with impressive results. In my system, I use one channel of a Streets 950 power amp w/ only 110wpc --equipped with an extra binding post for use when motional feedback is desired-- to drive a single Clark Contra Bass sub (2 x 12" cones wired out-of-phase and bolted face-to-face, downfiring), to produce deep bass in a smallish room that outperforms anything I have heard in a showroom anywhere. The Clark actually sits next to my listening seat. No one can tell the bass is coming from 2 feet away to one side.
One more thing helps with tight sub-bass control. Minimize speaker cable impedance. A long-ago TAS article introduced me to #4 welding wire. Thick, black, fugly, but cheap & flexible & all to terminate with big copper spade lugs. Works. ’Nuff said.

Hello watcher,

      You stated your room size is 16x30. The speakers are placed on the 16' side, and you sit about 11 feet away from the speakers. The SB are located right under the main, 6" from the wall.
    Instead of specific procedures on steps to take, I decided to just generally discuss the important areas of concern and the variables you're able to control. I'll provide specific procedures only when the areas of concern allow such specificity.

1. The Optimum Positioning of your 4319s:
    I went to the Cardas website linked below and read their suggestions for positioning a pair of stereo speakers in a rectangular room. I'm less confident on these suggestions than I am on the remaining areas of concern and my suggestions of steps you can take to address them.
          www.cardas.com/room_setup_main.php

    I just wanted you to realize this from the beginning and attached their link for your reference. I'd suggest you just follow their suggestions, determine for yourself how it performs in your system and room both sound performance wise and aesthetically and then experiment after with speaker placement adjustments that may perform better in your determination.
    According to Cardas, the optimum positioning of your 4319s would be with them positioned 7.5' apart from each other, 7.5' out or away from your front 16' wall, each speaker 4.4' away from the nearest side wall and with your listening seat exactly between the speakers and 7.5' away. They state that this is the recommended starting positioning and that making a series of small speaker position and toe-in angle adjustments are required to fine tune the stereo imaging, with the presence of a realistic, solid and stable soundstage illusion of vocals and the vocalist between the speakers being a good measure of positioning success.    

2. Procedure for optimizing the phase control settings on all four subs for improved subs and speaker integration:

A. Invert the polarity on both speakers by reversing the positive and negative speaker wire connections on the 4319's terminals only (NOTE: do not reverse the speaker wire connections on the amplifier, just reverse the speaker wire connections on the speakers). IOW, instead of the proper connections on the 4319 speaker terminals and speaker wires being pos. to pos. and neg. to neg., reverse them to pos. to neg. and neg. to pos.
B. Play some music with good and repetitive bass and sit in your listening chair.
C. With only Sub#1 powered on/active and both 4319s playing, have an assistant very slowly rotate the Continuously Variable Phase Control on Sub#1 until the bass sounds the weakest and worst to you.

D. Leave Sub#1's Phase control at this setting since the sub and 4319s will be both precisely in-phase once the 4319's polarities are not inverted and returned to normal.

E. Repeat steps A-D for Sub#2-4

F. When all 4 subs have had their Phase control set in this manner, return the speaker wire connections on both of the 4319's speaker terminals to the normal, pos. to pos. and neg. to neg., positions.

    This polarity inversion method works well because it's easier to
determine when the bass sounds the weakest and worst than the strongest and best.  
    The remaining two sub controls useful for optimizing the blending, or seamless integration, of the very good bass produced by your new 4-sub DBA system and the very good midrange and treble produced by your pair of JBL 4319s are the Volume and Crossover Frequency control settings on all four subs. Unfortunately, I'm unaware of a simple and effective procedure, like the one described above for optimally setting the Phase control, for optimally setting the Volume and Crossover Frequency
controls.  
    Based on my experience using a 4-sub DBA system, I consider the specific actual positions of the Volume and Crossover Frequency controls as the most important determinants of how well the bass produced by a 4-sub DBA system will blend, or seamlessly integrate, with the main speakers, as separate controls that are actually very interdependent in terms of their ability to influence the overall sound and performance quality of the combined system and as controls that are likely to be readjusted periodically over time as experience is gained and personal overall system preferences develop. Hopefully, you understand why I'm unable to offer simple procedures on how to set these controls and you quickly become proficient at setting them yourself on your new 4-sub DBA system.
     
    However, I can offer some advice and guidance.  The Volume control setting was probably the simplest for me to set since I don't want the bass to be overemphasized in my system. If you feel the same, then it's just a matter of matching and setting the Volume level on each of your four subs to the relative volume of the midrange and treble frequencies played back by your main speakers. The Swarm system requires only the setting of a single volume level on the amp/control unit, which I have set at 11:00 which is about 45%, but your custom DBA requires the desired relative volume to be set on each sub individually.
    The Crossover Frequency requires a bit more planning and experimentation. First you need to determine the bass extension limit of your main speakers, a good indication is the published rated frequency response figure usually stated as a specific frequency range capacity listed in hertz which indicates the upper and lower frequency limits along with a decibel deviation in output over the entire specified frequency range. For example, my Magnepans are rated at  34Hz-26kHz +/- 3dB, 34 Hz -3dB being the important figure for the bass extension limit.  Your JBL 4319s are rated at 38Hz-40kHz -6dB, 38Hz -6dB being the important figure for the bass extension limit. Since 3dB is the smallest change in loudness humans typically can notice, -6dB at 38Hz indicates that the bass will output at that frequency will be noticeably lower.
       Second, you need to decide whether you'll run your main speakers full-range or limit their bass output to a certain limit, I believe the built in filters on your SB and PB subs only allow limiting your main speakers bass output to a fixed 80 Hz and below.
     I did not perceive any sound quality benefit on my system by restricting the bass frequencies my amps and main speakers were responsible for reproducing so I run my mains full-range and usually have my Crossover Frequency set at 40 Hz, which means my Swarm DBA is reproducing the bass from 20-40 Hz.  
     However, I suggest you try both options and decide for yourself whether running your 4319s full-range or with restricting their output to 80 Hz sounds best to you.  If you prefer them running full-range, I'd recommend initially setting the Crossover Frequency on each of your subs to  45 Hz and then experiment by progressively decreasing the Crossover Frequency on each sub as low as possible while still liking the overall system sound quality.  If you prefer them running with the bass restricted to 80 Hz, I'd recommend initially setting the Crossover Frequency on each of your subs to 85 Hz and then experiment by progressively decreasing the Crossover Frequency on each sub as low as possible while still liking the overall system sound quality.  
     For best overall results, I'd also recommend initially setting the Volume level on each of your subs to your best estimate level and then experiment by progressively decreasing the volume on each sub as low as possible while still liking the overall system sound quality. 
     Remember, the goal is not to constantly be aware of your upgraded bass performance, the goal is for your overall system to effortlessly reproduce whatever bass the music, or any HT content, calls for whether it's accurate, detailed, quick,taut and rhythmic bass or accurate, detailed, sudden, deep, dynamic and powerful bass.


Enjoy,
Tim